Compressor controlling mechanism



June 21, 1932. A. MAXSON COMPRESSOR CONTROLIJING MECHANISM FiledNo 21, 1929 Inca $04 I A; l-wm,

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Patented June 21, 1932 1 UNITED STATES MAXSON, OF CLAREMONT, NEW HAMPSHIRE ASSIGNOR TO PA TQF T COMPRESSOR CONTROLLING MECHANISM Application filed November 21, 1929.: Serial No. 'eos,ss2..

invention relatesto mechanism for automatically controlling the loading and unloading of a compressor in accordance WllllI'tllG receiver pressure.

One object of my invention is to provide improved controlling means for the mechanism which governs a compressor, mechanism. Another object of my invention is to provide improved controlling mechanism designed to delay loading of the compressor when the same is starting from rest. A further object of my invention is to provide improved mechanism for actuating an unloading device for a compressor by vacuum and controlling such unloading in accordance with receiver tank pressure. Further objects of my invention will become-apparent in the course of the ensuing description, and be more paticularly pointed out in the appended claims.

In theaccompanying drawing, in which I i have shown, for purposes of illustration, one

intercooler 7. Any suitable prime mover 5 may be employed for driving the compressor;

embodiment of my invention:

Fig. 1 is a diagrammatic view of a compressor with its unloading mechanism controlled by a system in which my invention is incorporated.

Fig. 2 is a detail sectional view of a valve controlling the line between the vacuum pump and the unloading mechanism for the compressor; In the illustrative embodiment which is shown in the drawing, my improved control- -"ling system isshown appliedto an angle compound compressorv having a low pressure cylinder 5, a high pressure cylinder 6 and an but for purposes of illustration, I have shown as driving means a synchronous motor;

.8 Whosefield is supplied with current from an exciter 9, which is driven in any usual manner., The'fluid compressed by the high pressure cylinder 6 is conducted to a receiver tank 10, from. which it may be supplied for use as required. Theinlet 11 to the low pres sure cylinder 5 may be closed by a sleeve valve'12, so as to unload the compressor. A valve rod 13 is passed through the hub 14 of d j SULLIVAN MA--"' CEINEBY COMPANY, A conronar on or mnssnonnsurrs the sleeve-valve 12. "Devices 15 are mounted.

on rod 13, to engageopposite sides of the hub 14:. Theweight of the valve and associated parts would move it to closed position, but

if desired a weight 16 may surroundthe' rod 13, and restupon the upper'collar 15; and

help to move the sleeve valve 12into closed position. A motor is mounted at theupper' end of rod 13' for moving the same. Various types. of motors maybe used, which are adapted to be actuated by a vacuum;,but for purposes of illustration, I have shown a cylinder and pistonpl8 and 17 with the piston 17 connected to the rod 13.

A vacuum pump 20 is mounted onthe side of the base or the compressor, and iswactue ated by a link 21 driven from the compressor crank shaft 22. A pipe line 23 connects this vacuum pump} 20 with thecylinder18. An adjustable bleeder 24 may be arranged in the pipe line 23; and is so adjusted as to per mit suflicient air to enter the pipe line 23' during the lesser speeds of the compressor to prevent lifting of the sliding valve 12. The bleeder 2A is set so that the vacuum pump 20 willpumputhe pressure in the cyl-, inder 18 low enough to raise theslide valve 12 just before the compressor comesfto full speed. A valve 25 is also arranged in the pipe line 23 between the bleeder 24 and the section in'Fig. 2 and comprises a rotatable element 26 formed with passageways so that the cylinder-18 may be connected either to the vacuum pump 20, or to a vent 27 in. the casing 28 of thejvalve 25.. A lever 29 is-se cured to the rotatable element 26,so as to" rotate the same. The armature .ofa solenoid 30 is connected by link. to the lever 29 for actuating the same.v This solenoid is included ina circuit which is supplied, with current from the exciter 9 for the motor 8. "A pressure switch 31 is also includedin this circuit; and is controlled by the pressure in the receiver tank 10. For this purpose the switch comprises a "diaphragm lcolmectedby a P p line 33 to the receiver cylinder 18. This valve 25 isshown'in cross tank 10. A spring 34 normally retains the switch 31 in closed position. The spring tension is adjustable so that the switch 31 will be opened when a predetermined pressure is exerted upon the diaphragm 32. When the pressure switch 31 is opened, the solenoid "50 13, of 1 course, deenergizd and, K due to a weight or spring acting'on the armature, the lever '29swings downto'turn 'the valve element26rintoisuchiptositiomasltotcone nect the cylinder 17 iwith'athecatmosphene. .7

The operation of my improved control sys tem is as follows: Duringnormalrunningof the compressor, the slide valve 12 is in raised 15 position, due to the vacuumpumpedpythe vacuum pump As,pressure varies in the ireceivertanklllhthe same pressure variations are exerted ;on the diaphragm 32, TThe pressure ,1 switch 31 "will open iii 'a predetermined pressure, for which the spring 34- 18 tensioned, is "exceeded; whereupon the solenoid BO is rdeenergized .and the valvel opens .the cylinder 118 to thevatmospherer This-apermits-lthe weight. 16 to. force'the slide-valve 12 mm closed position, unloading the com- I pressor. i, V

:When the receiver tank pressure ftallslbe- .low ra:lower predetermined point, the spring 34closes-theswitch '31 .andcenergizesthe .sole- 1 1 'noid 30 so -as to' elevate the} lever 29, into positionto connect the cylinder 18 tothe vacuum' pumpQO. Thiszraisesrthe' slide valve 1 2, .:so asito open therinlet 111 ;.and .the compressor Iisggainloaded.

The operation when starting vuplfrom rest its as follows :The slide valve1'2 will be in lloweredposition, due-tolthev admission .o'fhair through the l bleeder '24, or :through the :vent -l2 7 in the casingi'2'8 ofsthe valve 125. If .the

f latter be true, thatlis to say,if.the;pressure switch :31 isiin ,position tounload thezcom- -.pr essor, theacompressor comes up vto speed and continues to run unloaded untilthejpresisureiinltheireceiver tank110 dropslto a point which produces ,closing of the pressure switch-31. Should, however, .the ventI27 be i closed and the cylinder :18 a connected r to the vacuum pump-20, the ibleeder 2 will admit -:suflicient:airzsozthatitheslide valve 12yvillre- .-Imain in loweredpositionruntili the compressor :comes -=substanti-al ly :up to inormal running ifspee'd. Justaprioreto 'rea'ching norm al run- :ning speed, the vacuum pump :is driven at 5 's ufiicient F speed to -lower th'e'ipressure inacyl- -'-'inder *18to a point where atmospheric'ipressure act'ingon the lower face of the piston 17 xwilllift theislidewalvel2.

It will 'sbe, apparent thatfas *a 'r ov'ed system, for unloading a compressor. fIt'will 'furthermore be apparent that my invention .provides improved controlling mechanism .ifor l theiloading and unloading of the com- ,pressor which; in an: improved ,manner, .pre-

esultofmy o invention I have provided an -im'pr vents loading of the compressor until the same has come up to speed. 7 While I have in this application spe cifically described one form which my invention may assume in practice, it will be understood that this form of, the same is shown j'for purposes :of illustiiatimn andithat the invention maybe modifiedand embodied in various' other forms without departing from its'spiritorltlre :SCOTPGEOf.tlIBPEPPGIldECliClBLlIIIS. 1 iWhat'Lclaimfas "IIEWTELIIClCdGSlIQ to secure by Letters Patent is -1; In =acompressor controlling system, a valve whose positiondetermines the loading "and unloading er the compressor, actuating :means theretore .operablewhensubjected to .a ,predetermined subatniospheiiic pressure, means driven byithelcompressor iorcre'ating -asubatmosph eric pressure fona ctin'g .on said zernedbynompr-essoridischarge. pressureivaris 1 ations and operative during continued .runningjloff ;the compressor for controlling said valve controllinglflow.of'fluid through said conduit.

.a vcompressor gcontrolling system, a I valve :whose position determines .therloafding and unloadingio f;v the (compressor, and means 0 .for moving said valve comprising [means tending to move ,said valve, into v position .to gunload the .compressor,: means actu ated when subjected to a predetermined subatmo spheric ,pressure fopmovingsaid valve, into position tolloa d the compressor, and means responsive V .tolth-e speed o fthecompressorandcommunicating with said third mentioned .means for i creating .isufiicient vacuum ,toloa d ,the comgpressorrwhen the samecomes uplto speed, AQIn combination with a compressor, means'lactuated toloaiding positionlwhen subjected to :a predetermined .subatmospheric 1 pi essuregfor controlling-loadingand-Iunloadg ingaof ,said compressor, a vacuumgpump o driven in accordance with the speed ofrthe compressor for creating cazsubatmospheric .pressurelfor actingon saidIcontrolling means,

pressure to which said controlling means is subjected during loaded operation of the compressor, upon an increase in the discharge pressure of the compressor beyond a predetermined amount;

5. In a compressor controlling system, an unloader valve, actuating means therefor controlled by subatmospheric pressure, means for maintaining a subatmospheric pressure during running of said compressor, and means for controlling connection of said actuating means with said means for maintaining subatmospheric pressure controlled by compressor discharge pressure.

6. In a pumping system, in combination, a pump, an intake unloader therefor, means including an element responsive to subatmospheric pressure conditions for moving said valve to loading position, a second pump actuated with said first pump for producing subatmospheric conditions, and means controlled by pressure variations produced by running of said first pump controlling connection of said second pump with said element.

7. In a compressor controlling system, a valve whose position determines the loading and the unloading of the compressor, actuating means for moving said valve to loading position when subjected to a predetermined subatmospheric pressure, a vacuum pump operative to produce said predetermined subatmospheric pressure when said compressor is operating at normal speed, means for connecting said vacuum pump with said actuating means to subject the latter to the vacuum produced by the former, and means governed by compressor discharge pressure for breaking the vacuum at said actuating means when compressor discharge pressure reaches a predetermined maximum.

In testimony whereof I afiix my signature.

LOUIS A. MAXSON. 

